It's hard to conjecture if Old Head would be rated higher by some (most even) were it located in the states. As Padraig mentions it is a great golf experience, and one that I've enjoyed numerous times. Some spectacular holes (2, 3, 4, 7, 12), and not solely because they are cliffside. Some more mundane holes (1, 18) and one downright silly (IMO) (17). No doubt the requirement to put 18 holes, a practice area and a world class clubhouse all contributed to some design challenges.
It's as unfair to compare it to those links' greats such as Lahinch, Ballybunion, etc. as it would be to compare it to Fota Island. Yet, since most of us Yanks cram these courses in on the same trip, such comparison is inevitable.
But conjecture I will --- Were Old Head located here, I think there would be more polarized opinions about it. I suspect the PR machine would keep the tee times chock full, but many a 'purist' would scoff at it.